In removing paint from painted surfaces one generally uses solvents that erode the paint or bring cause it to swell up. Subsequently, the paint is removed through mechanical means. The use of solvents leads to a substantial pollution of the environment. Chromate mixed with solvents is difficult to remove from the solvent. Furthermore, a considerable part of the solvents evaporate into the atmosphere.
It is known that a high-energy air jet having abrasive particles can be directed against a painted surface. The abrasive particles can be synthetic granulated material, glass spheres, nut shell fragments or CO.sub.2 ice crystals. Such abrasive processes are disadvantageous, wherein not only the paint is removed but also the surface underneath the paint is damaged. In particular, when the surface consists of artificially reinforced material, the danger exists that the reinforced fibers will be exposed by the spraying of abrasive material, so that the painted surface, in which the paint is to be removed, will be seriously damaged.
Furthermore, it is known that for cutting concrete and other material and for the purpose of cleaning the facade of buildings high-energy water jets are directed at the surfaces. The process of high-energy water jets is also used for rust-removal and removing shell-lime deposits on off-shore structures, such as, for example, ships and off-shore drilling platforms.
It is an object of the invention to provide a device for the removal of paint from painted surfaces, whereby the pollution of the environment is minimized and the removal of paint from painted surfaces is realized.
In accordance to the invention, the device consists of a rotating head having at least one nozzle, wherefrom a high-energy liquid jet is discharged. The rotating head is caused to rotate by the pressure of the high-energy liquid jet (in particular, through the recoil thereof), so that a separate rotating device in the housing is not required. By the rotation of the rotating head and the nozzle provided thereon, a periodically pressurized admission of approximately 150 to 220 Hz is directed to individual positions of the surface. As a result of the increase and decrease of the pressurized admission, the cohesive force of the paint is overcome and the paint of the surface splinters off. Thereby the lacquered coating as well as the primer can be disengaged. The rotating head is located in the inner part of the housing, the opening of the housing being closed by the surface to be treated.
Thus, the housing encloses the treated area completely. It can be guided over the painted surface by hand or by a suitable guiding device, so that a progressive treatment of the larger surface is possible. Uncontrolled liquids are prevented from being spun into the surroundings by the closed housing. Furthermore, the level of noise is reduced. The liquid and the paint disengaged from the surface is discharged out of the housing by the impeller. The impeller constitutes a centrifugal pump in the inner part of the housing, whereby the pump does not impede the high-energy jet discharged from the nozzles and removes the suspension from the housing immediately after the origination of the suspension. Thereby it is guaranteed that the high-energy liquid jets are not obstructed by a liquid layer that is to be found on the surface.
In accordance to the invention, the device requires only a connection to the housing for the pressurized fluid and no additional drive or supply lead. Thereby, the device is easily guided over the surface to be worked upon.
The device is particularly suitable for the removal of paint from painted surfaces which consist of metal or plastic. Aircrafts have their paint removed and are repainted every four to six years. This removal of paint proceeds in a hangar where other maintenance or repairs to the aircraft are also carried out. The device can be employed without any impairment or danger to people who are entrusted with other duties on the aircraft, whereby the device is always effected only on that position it is applied. The spraying of liquids as well as the level of noise is avoided. The outer shell of the aircraft consists of aluminum alloy and partially of carbon fiber solid solution. Both materials can have paint removed from their surfaces with this same device.
However, in accordance to the invention, the application of the device is not restricted to the removal of paint from painted surfaces of aircrafts. It can also remove paint or an equivalent coating of any other painted surfaces. Thereby it is also possible with equivalent miniaturized developments to utilize the device for the removal of paint from fingernails.
The removal of paint is caused by a periodically pulsed pressurized admission of a high-energy liquid jet. Thereby solvent-free liquids can be used. The removal of paint is particularly successful with water. The removal of non-soluble paint particles from the water can be realized through sedimentation or other separating systems, so that no polluted water appears in nature. The paint material can, in such a case, be recycled.
The rotating impeller together with the rotating head rotating more than a thousand times per minute, centrifuges the suspension out of the housing to the discharge valve. A prerequisite for this function of the impeller is that the impeller, in particular the rotating head, is not impeded by a collection of liquids in the housing. If the paint removal device must be used in different positions, for example on a horizontal surface, vertical or diagonal surface and overhead the collection of fluids can be thereby prevented in each of these situations in that the impeller is situated at end of the rotating head facing the opening. The impeller is also effective directly in the vicinity of the treated surface on which the leading edge of the impeller's blade is guided along. Thereby, it is guaranteed that the liquid is directly caught by the impeller after impact on the surface and is radially centrifuged so that no collection of liquid can build up that impedes with the rotation of the impeller blades and the rotating head.
A preferred embodiment is described in greater detail with reference to the accompanying drawings, as follows: